AbstractSolanum nigrumis a self-pollinating, hexaploid weed and one of a fewSolanaceaespecies native to Europe. It used to be described as a non-host forPhytophthora infestans. However, now it is known that, like its distant relatives: potato (Solanum tuberosumL.) and tomato (Solanum lycopersicumL.),S. nigrumcan suffer from potato late blight caused by this pathogen. Both susceptible and resistantS. nigrumgenotypes have been previously identified and inheritance of resistance originating from one accession has been described based on population of F2plants and 15 F3lines. The goal of this study was to evaluate resistance of three families of F3lines, originating from crosses between a susceptible and three different resistantS. nigrumaccessions followed by two self-pollinations. Parental accessions were tested for the spectrum of late blight resistance against 48P. infestansisolates. The three families consisted of 106, 96 and 115 F3lines, respectively, and from each line 20 plants were tested for resistance toP. infestans. Laboratory detached leaf assays were performed in two dates and two replications of three leaves each. Segregation of the trait within the line allowed us to distinguish hetero- and homozygous lines. In one F3family, the ratio of resistant homozygotes: heterozygotes: susceptible homozygotes was 1:2:1, indicating that a single gene is most likely underlying the late blight resistance in this case. In the other two, observed segregations of the trait significantly deviated from this model suggesting more complex inheritance patterns.